Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Treatment success
Systematic review	Adults with acute uncomplicated appendicitis (no abscess or phlegmon) 5 RCTs in this analysis	Initial treatment failure (antibiotic: failure to achieve definite improvement without the need for surgery and hospital discharge without an operation; appendicectomy: failure to achieve pathologically confirmed appendicitis after surgery or another surgical indication for operation) 40/470 (9%) with appendicectomy 137/510 (27%) with antibiotics	OR 2.43 95% CI 0.94 to 6.33 P = 0.07 Significant heterogeneity: I² = 69%, P = 0.01 Heterogeneity not further explained		Not significant
Systematic review	Adults with suspected acute uncomplicated appendicitis (no abscess or phlegmon) 5 RCTs in this analysis	Overall treatment failure (initial treatment failure plus anyone in the antibiotic group requiring appendicectomy because of recurrence) up to 1 year 40/470 (9%) with appendicectomy 205/510 (40%) with antibiotics	OR 6.72 95% CI 3.48 to 12.99 P <0.00001	Moderate effect size	appendicectomy
Systematic review	Adults with acute uncomplicated appendicitis (no abscess or phlegmon) 5 RCTs in this analysis	Overall complications (e.g., surgical site infection, organ space infection, small bowel obstruction, other) 60/510 (12%) with antibiotics 83/470 (18%) with appendicectomy	OR 0.54 95% CI 0.37 to 0.78 P = 0.001	Small effect size	antibiotics
Systematic review	Mainly adults, mean age 28.2 years (range 13–75 years), suspected acute appendicitis based on disease history, clinical status, and laboratory findings 5 RCTs in this analysis	Mean cure (within 2 weeks [free of symptoms such as abdominal pain, fever, inflammatory parameters] and without major complication [including recurrence] within 1 year) 97% with appendicectomy 73% with antibiotics Absolute numbers not reported	The review pooled data for each group and calculated 95% CI Appendicectomy: 97% (95% CI 94% to 99%) Antibiotics: 73% (95% CI 63% to 82%) Mean cure rates were higher with appendicectomy, but the review did not report a between-group P value
Systematic review	Mainly adults, mean age 28.2 years (range 13–75 years), suspected acute appendicitis based on disease history, clinical status, and laboratory findings 5 RCTs in this analysis	No major complications (including the need for further [invasive] treatment or prolonged admission [e.g., abscesses, ileus, deep wound infection, recurrence, re-operation, secondary perforation]) 97% with appendicectomy 83% with antibiotics Absolute numbers not reported	The review pooled data for each group and calculated 95% CI Appendicectomy: 97% (95% CI 93% to 99%) Antibiotics: 83% (95% CI 72% to 91%) Proportion of people with no major complications was higher with appendicectomy, but the review did not report a between-group P value
Systematic review	Mainly adults, mean age 28.2 years (range 13–75 years), suspected acute appendicitis based on disease history, clinical status, and laboratory findings 5 RCTs in this analysis	No minor complications (e.g., superficial wound infections, negative appendix at histology [no appendicitis], diarrhoea, urinary tract infection) 91% with appendicectomy 96% with antibiotics Absolute numbers not reported	The review pooled data for each group and calculated 95% CI Appendicectomy: 91% (95% CI 83% to 96%) Antibiotics: 96% (95% CI 93% to 97%) Proportion of people with no minor complications was higher with antibiotics, but the review did not report a between-group P value
Systematic review	Adults with a diagnosis of uncomplicated acute appendicitis	Complications (antibiotics: perforated or gangrenous appendix, peritonitis, or wound infection [in people who failed antibiotics and had appendicectomy subsequently]; appendicectomy: perforated appendicitis, peritonitis, or wound infection) 84/470 (18%) with antibiotics 108/430 (25%) with appendicectomy	RR 0.69 95% CI 0.54 to 0.89 P = 0.004	Small effect size	antibiotics
Systematic review	Adults with a diagnosis of uncomplicated acute appendicitis	Risk of complicated appendicitis 54/470 (11%) with antibiotics 131/430 (31%) with appendicectomy	RR 0.46 95% CI 0.19 to 1.12 P = 0.09 Significant heterogeneity: I² = 82%, P <0.001 A sensitivity analysis removing 1 RCT with high crossover found a similar result, but there was still significant heterogeneity among groups (RR 0.58, 95% CI 0.18 to 1.90; I² = 74%)		Not significant